classic hacks

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Creating GIFs For The Channels Between Channels

March 17, 2023 by 4 Comments

In the United States, analog TV broadcasting officially ended in 2009. While the transition wasn’t without hiccups, we did lose something along the way. For [Emily Velasco], she misses the channels between channels — where an analog TV isn’t quite tuned right and the image is smeared and distorted. A recent bug in one of her projects led to her trying to recreate the experience of the in-between on a CRT.

One of [Emily]’s other projects involved generating composite video signals from an ESP32 microcontroller. While experimenting with adding color to the output signal, the image came out incredibly scrambled. She had made an error in the stride, which smeared the image across the screen. This immediately brought back memories of old analog TV sets. A quick potentiometer allowed her to control the stride error and she wrote some code to break the GIF up into discrete bitmaps for display since the GFX library handles GIFs differently than static images. Next up was vertical hold, which was accomplished by shifting the Y coordinates. With some help from [Roger], there was now a handy GIF library that would draw GIFs line by line with the composite video effects.

She used a Goldbeam portable CRT, soldered the tuning potentiometer to the ESP32, and set up 10 different GIFs to act as “channels” with space in between. It’s a fun and quirky idea, which is exactly the sort of thing [Emily] has been encouraging people to do.

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A Retro-Style Trainer For Motorola’s 1-Bit Chip

March 11, 2023 by 6 Comments

If you want to program a microcontroller today, you pop open your editor of choice, bang out some code, and flash it over USB. But back in ancient times, when your editor was a piece of paper and you didn’t even have a computer of your own, things were a bit different. In that case, you might have reached for a “trainer”: a PCB that included the chip you wanted to program along with an array of switches, LEDs, and maybe even a hex keypad for good measure. Grab yourself the programming manual (printed on paper, naturally), and you’re good to go.

So when [Nicola Cimmino] became curious about the Motorola MC14500, a 1-bit ICU (Industrial Control Unit) from the 1970s, he could think of no more appropriate way to get up close and personal with the chip than to design an era-appropriate trainer for it. The resulting board, which he’s calling the PLC14500 Nano, is festooned with LEDs that show the status of the system buses and registers. Thanks to the chip’s single-step mode, this gives you valuable insight into what’s happening inside this piece of classic silicon.

An early breadboard version of the trainer.

But just because the board looks like it could have come from the 1970s doesn’t mean you have to live in the past. There’s an Arduino Nano on the backside of the trainer that handles communicating with a modern computer. [Nicola] even provided an assembler that lets you write your code in ASM before shuttling the binary off to the board for execution.

Interested in getting your hands on one? Not a problem. The design is completely open source for anyone who wants to build one at home. In fact, [Nicola] even got his trainer OSHW Certified. He’s also selling kits on Tindie, though at the time of this writing, they’re sold out.

This project has actually been a long time coming. We covered an early breadboard prototype of the concept back in 2015. We’re glad to see that [Nicola] was finally able to bring this one across the finish line. It’s a beautiful piece of hardware, and thanks to its open-source nature, something that the whole community can enjoy and learn from.

Old TV To RGB

March 8, 2023 by 19 Comments

As CRT televisions have faded from use, it’s become important for retro gaming enthusiasts to get their hands on one for that authentic experience. Alongside that phenomenon has been a resurgence of some of the hacks we used to do to CRT TV sets back in the day, as [Adrian’s Digital Basement] shows us when he adds an RGB interface to a mid-1990s Sony Trinitron.

Those of us lucky enough to have lived in Europe at the time were used to TVs with SCART sockets by the mid-1990s so no longer needed to plumb in RGB signals, but it appears that Americans were still firmly in the composite age. The TV might have only had a composite input, but this hack depends on many the video processor chips of the era having RGB input pins. If your set has a mains-isolated power supply then these pins can be hooked up with relative ease.

In the case of this little Sony, the RGB lines were used by the integrated on-screen display. He takes us through the process of pulling out these lines and interfacing to them, and comes up with a 9-pin D connector with the same pinout as a Commodore monitor, wired to the chip through a simple RC network and a sync level divider. There’s also a switch that selects RGB or TV mode, driving the OSD blanking pin on the video processor.

We like this hack just as much as we did when we were applying it to late-80s British TV sets, and it’s a great way to make an old TV a lot more useful. You can see it in the video below the break, so get out there and find a late-model CRT TV to try it on while stocks last!

Unsurprisingly, this mod has turned up here a few times in the past.

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This Retro Game Console Puts Vacuum Fluorescent Display To Good Use

March 7, 2023 by 4 Comments

Small in size, low-resolution, blocky segments, and a limited color palette — all characteristics of the typical vacuum fluorescent display, any of which would seem to disqualify them as the display of choice for a lot of applications. But this is Hackaday, and we don’t really pay much attention to what we’re supposed to do, but rather to what’s fun and cool to do. So when we see something like a VFD game console, we just have to sit up and take notice.

In a lot of ways, the design of [Simon Boak]’s Arduino-based VFD console is driven by his choice of display. The Noritake Itron GU20X8-301 VFD is a “tricolor” display with eight rows of 20 rectangular pixels. Each pixel is composed of six short linear segments, with alternating red and blue colors. Turning on either set of segments yields one of the two base colors, while turning on both yields a sorta-kinda whitish color, if you squint a bit.

[Simon] chose a two-piece design for his console, with a separate controller and display. The controller holds the Arduino Nano and all the controls, plus a piezo buzzer for fun. The display case connects to the controller with a ribbon cable and holds the VFD power supply and driver. To celebrate the retro look of the VFD, both cases are decked out with woodgrain side panels. [Simon] chose appropriately blocky games for the console, like Snake, Conway’s Game of Life, and the venerable snow demo. We’d imagine Pong would be a good choice too, as well as perhaps Tetris if the display were flipped on its side.

We really like the look of this console, and we appreciate putting an otherwise obsolete display to use in a creative way. If you want to learn a little more about these displays, check out this love letter to the VFD.

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A Medium Format Camera From Scratch

March 5, 2023 by 12 Comments

Film photography may now be something so outdated as to be unknown to our younger readers, but as an analogue medium it has enjoyed a steady enthusiast revival. There is still a bonanza of second-hand cameras from the days when it was king to be found, but for some photographers it’s preferable to experiment with their own designs. Among them is Reddit user [elelcoolbeenz], who has produced their own medium format camera for 120 roll film.

The camera has a plastic 3D printed body and a single meniscus lens, and perhaps most interestingly, a 3D printed shutter too. It’s heavily reminiscent of the Holga and Lomo plastic cameras that have carved a niche for themselves, and it gives the same photographic effects from its dubious quality optics.

There’s a snag of course, that the STLs are not yet available We say not yet, because this comes with a detailed explanation in that further work is required on the shutter and a more commonly available lens is found rather than a one-off. We still think it’s worthy of featuring at this stage though, because it serves to illustrate that building a camera is not impossible. We’d love to see more of them, though we expect few of them to go to the lengths this aluminium one did.

A Close Look At How Flip-Dot Displays Really Work

March 3, 2023 by 15 Comments

[Mike Harrison] has an upcoming project which will combine a large number of flip-dot displays salvaged from buses. [Mike] thought he knew how these things worked, and had a prototype PCB made right away. But while the PCB was being manufactured, he started digging deeper into the flip-dot’s flipping mechanism.

As he dismantled one of the flip-dots, he realized there was a lot going on under the hood than he realized. The dots are bistable — staying put when power is removed. This is achieved with a U-shaped electromagnet. The polarity of a driving pulse applied to the coil determines which way to flip the dot and saturates the electromagnet’s core in the process. Thus saturated, each dot is held in the desired position because the black side of the dot is made from magnetic material. But wait, there’s more — on further inspection, [Mike] discovered another permanent magnet mounted in the base. He’s not certain, but thinks its job is to speed up the flipping action.

Besides curiosity, the reason [Mike] is studying these so closely is that he wants to build a different driver circuit to have better and faster control. He sets out to better understand the pulse waveform requirements by instrumenting a flip-dot and varying the pulse width and voltage. He determines you can get away with about 500 us pulses at 24 V, or 1 ms at 12 V, much better that the 10 ms he originally assumed. These waveforms result in about 60 to 70 ms flip times. We especially enjoyed the slow-motion video comparing the flip at different voltages at 16:55 in the video after the break.

[Mike] still has to come up with the optimum driving circuit. He has tentatively has settled on a WD6208 driver chip from LCSC for $0.04/ea. Next he will determine the optimum technique to scale this up, deciding whether going for individual pixel control or a multiple sub-array blocks. There are mechanical issues, as well. He’s going to have to saw off the top and bottom margin of each panel. Reluctant to unsolder the 8500+ joints on each panel, his current idea is to solder new controller boards directly onto the back of the existing panels.

This video is a must-watch if you’re working on drivers for your flip-dot display project, and we eagerly look forward to any future updates from [Mike]. We also wrote about a project that repurposed similar panels a couple of years ago. There are a few details that [Mike] hasn’t figured out, so if you know more about how these flip-dots work, let us know in the comments below.

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A Thoroughly Modern Serial Terminal

March 1, 2023 by 16 Comments

The humble desktop serial terminal may have long disappeared from the world of corporate IT, but there are still plenty of moments when professionals and enthusiasts alike need to hook up to a serial port. Many of us use a serial port on our laptops or other mobile devices, but [Neil Crawforth] has gone one better than that with the VT2040. It’s an old-style serial terminal in a super-handy portable format, and as one might guess from the name, it has an RP2040 microcontroller at its heart.

Attached to the chip is a rather nice keyboard, and an ILI9488 480×320 LCD display. The software is modular, providing a handy set of re-usable libraries for the different functions including a PIO-based serial port. His main application seems to be talking to an ESP8266, but we’re guessing with a MAX232 or other level shifter chip it could drive a more traditional port. Everything can be found in the project’s GitHub repository, allowing anyone to join the fun.

As long-time readers will know, we’ve been partial to a few serial terminals in the past. Particularly beloved is this extremely retro model with vintage dot matrix LEDs.